Slurries, abrasives, dry product and many chemicals can be hard on shaft packing. Even with sufficient flush back pressure, dimensional wear and shaft runout can render packing all but useless in a matter of weeks, or even days. At this point, the only solution has heretofore been to shut down the associated system and repack the stuffing box.
Accordingly, it is an object of this invention to provide, in a stuffing box environment, a packing life extender ring assembly which includes a pair of annular rings each having a tapered surface thereon matingly engaging the other, the rings being made of a composition containing virgin polytetrafluoruethylene and calcium metasilicate.
It is a further object of the invention to provide a packing life extender ring assembly, as aforesaid, wherein the composition includes 60% to 85% by weight virgin polytetrafluoruethylene, the remainder being calcium metasilicate. The preferable composition is 75% by weight polytetrafluoruethylene, the remainder being 25% by weight calcium metasilicate. This composition includes materials that are suitable for use in the food processing industry and the pharmaceutical industry as well as other industries.